94: PRELIMINARY COLD STORAGE STUDIES. 



Discussion of Results Obtained in the Bureau of Chemistry, 

 histo-chemical changes in cold-stoeed chickens. 



Gautier a states that the muscle fibers of cold-stored flesh remain 

 unaltered except, perhaps, for a slight pulling apart of the indi- 

 viduals. The marked and deep-seated changes, the occurrence of 

 which has been demonstrated in connection with the study in this 

 laboratory, of chickens preserved by cold are. therefore, of interest, 

 and it seems probable that the solving of the problem of the cause, 

 sequence, and ultimate result of such changes would throw much 

 light on the whole question of the various alterations undergone by 

 flesh at low temperatures. TYTiile the various dyestuffs which have 

 been used to differentiate the tissues preparatory to microscopic 

 study have not. as yet. served as exact microchemical reagents in 

 the sense of classification of compounds, they have very positively 

 indicated an alteration in the chemical character of certain mor- 

 phologically distinct elements. 



The characteristic green of the normal, fresh muscle fiber, when 

 stained as previously described, is very decidedly altered by long 

 keeping at low temperatures, so much so that finally it is almost 

 entirely replaced by dirty yellow and brown greens, or even by orange 

 tints. The white fibrous connective tissue, staining a brilliant blue 

 hi the fresh chicken, in the cold-stored takes on a greenish tint. 

 The material which exudes from the muscles after keeping for even 

 a comparatively short time has. at first, almost the same staining 

 reaction as the fiber itself, but it changes gradually, until it is a dirty 

 brownish or bluish green. The irregular staining of the fiber would 

 also indicate the presence of a progressive chemical alteration. The 

 rupture of the sarcolemma and the extrusion of the muscle substance 

 are not merely mechanical alterations due to freezing and thaw- 

 ing. If such were the case the progressive effects which are so clearly 

 traced in fowls kept for periods of varying lengths of time would be 

 wanting. The differences between the chicken muscle frozen for 

 48 hours and that of the fresh bird lies chiefly in the size of the spaces 

 between the fibers or bundles of fibers, and deep-seated changes 

 are not seen. 



The histological alterations which have been traced are confirmed 

 by the differences noted between stored and fresh chickens in the 

 distribution of the protein nitrogen. It would seem probable that 

 for the chickens stored 2 years and 4 years, respectively, the greater 

 part of the change is due to enzyme action, not only because the 

 tissue shows but few bacteria either living or dead, nor because the 

 histological degeneration proceeds differently from that observed 

 when ordinary temperatures prevail, but also because of the changes 



o Loc cir. 



